1. CNS Pharmacology-
Introduction to Drugs of Abuse I
Clinical:
E-Medicine Article
Injecting Drug Use
Prepared and Presented by:
Marc Imhotep Cray, M.D.
Professor Pharmacology
2. Definitions
I. Drug abuse
II. Drug dependence
A) Psychological dependence
B) Physiological dependence
III. Drug addiction
IV. Drug tolerance
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3. I. Drug abuse
Inappropriate and usually excessive, self-
administration of a drug for non-medical purposes
Almost all abused drugs exert their effects in the CNS
Drugs with high abuse potential have a tendency to
induce compulsive drug-seeking behavior
Preoccupation with the procurement and use of the drug
may be so demanding as to decrease the users
productivity.
In addition, prolonged abuse may cause chronic toxicity
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4. II. Drug dependence
Repetitive use of substances that produce
an optimal state of well being because of
their positive reinforcing effects in the
CNS
A) Psychological dependence.
B) Physical dependence.
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5. II. Drug dependence
A) Psychological Dependence
Motivational component: great subjective need,
compulsion, drive to get the drug
Will take drug periodically
Although physical dependence for a drug may
not occur, “drug-seeking behavior” is present
Habituation; Just "like" the drug; Drug effects
serve as “positive reinforcers”
No tolerance increase
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6. II. Drug dependence
B) Physiological Dependence
The body needs the drug for normal
physiological function
Tend to increase dose because of tolerance.
Physical withdrawal symptoms (negative
reinforcement)
Predictable group of signs and symptoms
resulting from abrupt removal of a drug
Psychological dependence is also present
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7. III. Drug addiction
The drug-use and drug-seeking behavior of
dependent individuals is maintained by the
reinforcing central activity of the drug despite
its negative social, psychological and physical
consequences
Physiological effects, including negative
reinforcers such as symptoms of withdrawal may
also be involve.
High tendency to relapse
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8. IV. Drug tolerance
After chronic use, the
same amount of drug
is insufficient to cause
the desired effect and
thus, more drug is
used
A compensatory
responseDrug Dose
Normal
Tolerance
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9. IV. Drug tolerance cont.
A) Innate Tolerance
1. Sensitivity
2. Insensitivity
B) Acquired Tolerance
1. Pharmacokinetic or metabolic
2. Pharmacodynamic or functional
3. Learned or behavioral
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10. V. Cross-dependence
When a drug is administered to achieve
the same outcome as that of another
drug
i.e. heroin methadone
In a heroin user, methadone can be
substituted for heroin in preventing
the withdrawal syndrome
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11. VI. Cross-tolerance
When an individual has become tolerant to
a drug and requires higher than normal
doses of a second drug to have its effects
i.e. Barbiturates BDZ
Amphetamine Cocaine
BARBs Anesthetics
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12. VI. Cross-tolerance
In general there is cross-dependence and cross-tolerance
between drugs of the same class, but not between drugs in
different classes
There is some cross-tolerance btw sedative-hypnotics and
volatile intoxicants; thus a person tolerant to barbiturates will
require more anesthesia than a non-tolerant person
LSD type drugs (tryptamine group) and phenylethylamines
have cross-tolerance for each other but not with other
hallucinogens
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13. VII. Co-administration/Co-abuse
Drugs of abuse are used in combination with
other drugs from one or more categories
Alcohol is used, for example, with almost
everything else
Smoking (nicotine intake) is prevalent in
patients using other drugs
Be aware of the possibility of combination
of drugs when treating intoxication,
withdrawal or overdose, each drug will
require a specific treatment
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14. Take home Point
Because of the diverse character of these drugs,
there is no “single reason” for their use, nor is
there an “addictive personality".
IT IS NOT NECESSARY TO HAVE A PREEXISTING
EMOTIONAL OR PSYCHIATRIC PROBLEM TO
BECOME DRUG DEPENDENT!!!
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15. VIII. Toxicology
A) Tissue and organ toxicity
- Usual dose vs overdose
- Acute use (respiratory depression -
narcotics, coma-barbiturates;
cardiovascular effects and seizures-
cocaine;arrhythmias-volatile intoxicants)
- Chronic use (alcohol, tobacco)
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16. VIII. Toxicology
B) Psychic toxicity
- Acute use (bad trips, flashbacks -
hallucinogens; CNS stimulants).
- Chronic use (alcohol,
hallucinogens, stimulants =>
reality distortion).
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17. VIII. Toxicology
C) Behavioral toxicity
- Amotivational syndrome, loss of
productivity loss of psychomotor control,
accidents, violence
- Acute use (alcohol, stimulants, PCP)
- Chronic use (alcohol, CNS depressants,
stimulants, hallucinogens, PCP)
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18. VIII. Toxicology
D) Associated Diseases
- Infections, AIDS, venereal diseases,
tobacco-related fires, toxicity due to bad
batches of drug (MPTP, PCP congeners),
car accidents, big machinery accidents,
other accidents, violent death
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19. Also see:
Mouse Party University of
Utah, Genetic Science
Learning Center
The Science of Addiction
University of Utah, Genetic
Science Learning
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47. Drugs and Neurotransmitters & Mental
Disorders Interactive Tutorials and
Animation Learning Tools
Psychotropic Medications and Neurotransmitters
Wisconsin Online
Alcohol and the brain from PBS
The Effect of Drugs and Disease on Snaptic
Transmission Harvard Education
Nicotine Patch by Nucleus Communications
GABA Inhibition of Glutamate Bay Area Pain Medical
Associates
Acute Pain Bay Area Pain Medical Associates
How Drugs Affect Neurotransmitters INMHA
47
48. Drugs and Neurotransmitters & Mental
Disorders Interactive Tutorials and
Animation Learning Tools
Schizophrehia UNIVERSITY OF CENTRAL LANCASHIRE
Epilepsy UNIVERSITY OF CENTRAL LANCASHIRE
Pharmacologic Action of Meth RnCeus.com
How is Pain Produced University of Edinburgh
How Much Alcohol can YOU TAke BBC
The Brain: Understanding Neurobiology Through the Study of Addiction
National Institutes of Health
The Science of Addiction University of Utah, Genetic Science Learning
Center
Stimulants and Antidepressants Dr. Ian Winship of the University of
Alberta
Tranquilizers and CNS Depressants Dr.Ian Winship of the University of
Alberta
Genetics of Addiction Genetics Science Learning Center
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